Re: [PATCH net-next RFC 2/5] vhost: introduce helper to prefetch desc index
From: Stefan Hajnoczi <hidden>
Date: 2017-09-22 09:03:05
Also in:
kvm, lkml, virtualization
On Fri, Sep 22, 2017 at 04:02:32PM +0800, Jason Wang wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index f87ec75..8424166d 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c@@ -2437,6 +2437,61 @@ struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev, } EXPORT_SYMBOL_GPL(vhost_dequeue_msg); +int vhost_prefetch_desc_indices(struct vhost_virtqueue *vq, + struct vring_used_elem *heads, + u16 num, bool used_update)
Missing doc comment.
+{
+ int ret, ret2;
+ u16 last_avail_idx, last_used_idx, total, copied;
+ __virtio16 avail_idx;
+ struct vring_used_elem __user *used;
+ int i;The following variable names are a little confusing: last_avail_idx vs vq->last_avail_idx. last_avail_idx is a wrapped avail->ring[] index, vq->last_avail_idx is a free-running counter. The same for last_used_idx vs vq->last_used_idx. num argument vs vq->num. The argument could be called nheads instead to make it clear that this is heads[] and not the virtqueue size. Not a bug but it took me a while to figure out what was going on.